1. Field of the Invention
This invention relates generally to orthodontic treatment techniques and appliances and is particularly concerned with a device which can be attached to a fixed subperiosteal or intrabony anchor and from which forces can be generated to move teeth and correct malocclusions.
2. Discussion of the Prior Art
The use of fixed, immovable bony anchors as rigid objects from which to exert forces to move teeth has been considered in orthodontics for more than twenty years. See, for example, Sherman, A. J., "Bone reaction to orthodontic forces on vitreous carbon dental implants," American Journal of Orthodontics, vol. 74, p. 79, 1978, and Smith, J. R., "Bone dynamics associated with the controlled loading of bioglass-coated aluminum oxide endosteal implants," American Journal of Orthodontics, vol. 76, p. 618, 1979. These early studies used animal models. and it was not until 1983 that their use was demonstrated in clinical orthodontics. See Creekmore, T. A. and Eklund, M. K., "The possibility of skeletal anchorage," Journal of Clinical Orthodontics, vol. 17, p. 266, 1983. Thereafter additional reports of the use of a bony anchor from which to exert forces to move teeth have appeared See, for example, Turley, P. K., Gray, D. W., Kean, L. J. and Roberts, E. W., "Titanium endosseous and vitallium subteriosteal implants as orthodontic anchors for tooth movement in dogs," Journal of Dental Research, vol. 63A, p. 334, 1984, and Goodacre, C. J., "Rigid implant anchorage to close a mandibular first molar extraction site, Journal of Clinical Orthodontics, vol. 18, p. 693, 1994. More recently, interest has shifted to subperiosteal anchors as described by Block and Hoffman in U.S. Pat. Nos. 5,066,224 and 5,538,427, the article "A new device for absolute anchorage for orthodontics," Journal of Orthodontics and Dentofacial Orthopedics, vol. 107, p. 251, 1995 and in application of Devincenzo, application Ser. No. 08/948,731, filed Oct. 20, 1997. See also Kanomi, R., "Mini-implant for Orthodontic Anchorage," Journal of Clinical Orthodontics, vol. 31, pp. 763-767, 1997 and Sachdeva, et al U.S. Pat. No. 5,697,779.
All of the above mentioned anchor systems utilize either endosseous or subperiosteal placement and afford rigid, immovable objects from which teeth can be moved forward, backward, upward, downward and sideways. However, the surgical placement of these anchors in certain areas of the mouth is frequently very difficult because of limited access, thinness of the overlying soft tissue, irritations caused during routine oral functions, and the presence of nearby roots, nerves and blood vessels. Additionally. the means of attaching to these anchors is technically difficult and complicated mechanical objects are required to facilitate tooth movement and orthodontic corrections.
It is technically difficult to work in the back and roof of the mouth but the overlying tissue is thick. It is easy to work on the sides of the mouth opposite the upper teeth, but the overlying tissue is thin and irritation from the anchors and the presence of the roots of the teeth limit use in these areas. Right at the midline of the maxilla and mandible surgical access, tissue thickness and minimal irritation are present.